Troughs or open drains are an age old solution for removing and channeling excess waste fluids, a common example are rain gutters that are attached under the eaves of residential homes and other buildings. As long as open drains have been used there have been problems with them being partially or completely clogged either by debris contained in fluid carried by the open trough or debris simply settling in the open trough or both. Again, referring to the rain gutter example, rain water coming off the roof of a house may contain leaves, small branches, pine needles, roofing material, etc. which can clog the rain gutter, or leaves from trees may simply collect in the gutter as they fall from trees. The clogging problem is especially acute where the open trough feeds into a closed pipe such as a rain gutter down spout.
Attempts to remedy these problems have had mixed success. One of the apparently simplest solution is to simply suspend a screening material across the open portion of the effected trough. There are problems with permanently attaching the material on either side of the open drain. The weight of debris accumulating atop a screen suspended across an open trough can cause the screen to pull away from the suspension points if they are not sufficiently strong. At the same time in an application such as rain gutters on a building, the weight of any screen attachment system and its cost, both in terms of material and labor to implement an attachment system for a screen, need to be minimized.
In addition, the screening material must be such that it readily admits the water into the trough without itself being clogged by the debris. If the screening material is insufficiently permeable to the fluids, it will have the partial effect of diverting not only the debris from the open drain, but also directing the fluid from the open drain. If the screen material has a high permeability achieved by having large openings, there is the risk that it will not sufficiently perform its filter function and the open drain will become plugged.
Some other earlier efforts at alleviating the clogging problem have attempted to use screening material suspended over a separate frame which in turn is placed over its open trough. In such devices, the separate frame provides sufficient structural strength to prevent a collapse of the screening material from the weight of debris. While in some ways more effective than a flat screen suspended across an open drain, the use of a separate frame significantly increases the weight of the device, as well as the cost and complexity of assembly of the device.
Other approaches to solve the clogging problem use screening devices which are inserted into the open drain. As with a screen covering the top of the open drain, the screening device inserted within the open drain must balance permeability to the fluid against the filtering function to keep debris out of the open drain to prevent clogging. Also, it is important that the screen inserts have sufficient structural strength to prevent them from collapsing under the weight of the debris which would render them at best no better than the open drain alone and might actually contribute to the clogging problem.
Some inserts have used a metal mesh as a screening material to provide sufficient strength to the screen insert. Metal screen materials present problems with weight, cost, and fabrication for particular applications such as corners in the open drain. Also, since metal screening material is not generally resilient, if the screen insert is collapsed, it must be replaced.
Other screen insert devices have used solid porous material such as polyurethane foam in an attempt to address some of the problems with a metallic screen insert. These materials however are not sufficiently permeable to fluids and are therefore unable to effectively filter higher volumes of fluid, such as might be encountered by rain gutters in a rainstorm. In addition, many of these solid porous materials lack sufficient structural strength and require either additional structural supports to maintain their shape and position, or increased thickness which amplifies the problems of fluid flow.
As seen from the above discussion, there are a number of desirable characteristics for effective filters for troughs or open drains. It would be desirable to have an open drain filter which effectively filters debris from excess or waste fluids while allowing the fluid to pass relatively unobstructed. It also would be desirable to have an open drain filter which is lightweight, while at the same time having sufficient structural strength to prevent its collapse from the weight of accumulated debris. Further, it would be desirable to have an open drain filter that could be quickly and efficiently installed in new and already existing open drain systems without requiring special fittings or tools for the installation or fitting. In addition, it would be desirable to have an open drain filter that was both resilient, durable and corrosion resistant to minimize the need for replacement and repair.
While the discussion herein relates to a method and apparatus for open drain filters, it is not intended that the invention be limited to this situation. It will be obvious from the description that follows that the present invention will be useful in other applications with problems, to those described herein.